Objectives: Characterize the epidemiologic status of gastric cancer in Newfoundland and identify those environmental factors which may contribute to the pathogenesis of this disease. The descriptive and statistical analysis of gastric cancer mortality will be undertaken with respect to age-, sex-, regional-, and occupational factors. Correlations with geochemical factors will also be made, as well as with total mortality, cancer-specific (all sites) mortality, and other relevant diseases. Since it is hypothesized that an environmental factor(s), most likely related to an ingested detary constituent or contaminant, may be involved in the etiology of gastric cancer, systematic studies to define regional dietary differences with regional differences in gastric cancer mortality will be initiated. The quantitative composition of trace elements in drinking water will be analyzed regionally in Newfoundland. All of these factors (trace element composition, dietary differences, occupational factors) will be correlated with high and low risk geographic areas with respect to gastric cancer mortality in Newfoundland. The insular nature, small size, and "closed", stable population of Newfoundland, coupled with regional geochemical and occupational differences within Newfoundland create an ideal setting for an intensive epidemiologic study of this disease.